standard_vtol: transition at airspeed of 16 m/s

This way we prevent a big dip due to TECS in altitude when the
transition happens at 10 m/s already. Apparently the rule of thumb
is to set this transition speed at the same as airspeed cruise speed.

ROMFS/px4fmu_common/init.d-posix/1040_standard_vtol

@@ -34,6 +34,7 @@ then
 
 	param set VT_F_TRANS_DUR 5
 	param set VT_F_TRANS_THR 0.75
+	param set VT_ARSP_TRANS 16
 	param set VT_MOT_COUNT 4
 	param set VT_TYPE 2